Hydraulic marine propulsion system

ABSTRACT

A HYDRAULIC PROPULSION SYSTEM FEATURING AN INBOARD POWER PLANT AND FLUID PRESSURE-GENERATING SYSTEM AND AN OUTBOARD FLUID DRIVING SYSTEM, THE INBOARD PRESSURE-GENERATING SYSTEM CONSISTING OF REVERSIBLE VARIABLE DISPLACEMENT AXIAL PISTON PUMP, LEVER-OPERATED SERVOSYSTEM, SPEED CONTROL, CHARGE PUMP AND VALVE MANIFOLD UNITS AND THE OUTBOARD FLUID-DRIVING SYSTEM CONSISTING OF A FIXED DISPLACEMENT AXIAL PISTON FLUID MOTOR AND PROPELLER.

. United States Patent [72] Inventor Curt Buddrus 2522 Hayes St., Muskogee, Okla. 74401 [21] App1.No. 818,888

[22] Filed Apr. 24, 1969 [45] Patented June 28, 1971 [54] HYDRAULIC MARINE PROPULSION SYSTEM 10 Claims, 4 Drawing Figs.

[52] U.S. Cl 115/34,

[51] Int. Cl B63h 23/26 [50] Field oisearch l15/34,35, 34 (A),41,41(1-1T) [56] References Cited UNITED STATES PATENTS 1,198,093 9/1916 Williams 115/34(X) 1,827,438 10/1931 Rauch 1l5/34(X) 2,486,049 10/1949 Miller 115/34(X) 2,766,715 10/1956 Waterval ll5/34(X) 3,010,424 11/1961 Peterson et a1. 115/41 3,139,062 6/1964 Keefe 115/34(X) 3,234,856 2/1966 Martin llS/34(X) FOREIGN PATENTS 640,097 5/1962 ltaly 115/34A Primary Examiner-Milton Buchler Assistant Examiner-Carl A. Rutledge Attorney-James D. Halsey, Jr.

ABSTRACT: A hydraulic propulsion system featuring an inboard power plant and fluid pressure-generating system and an outboard fluid driving system, the inboard pressuregenerating system consisting of reversible variable displacement axial piston pump, lever-operated servosystem, speed control, charge pump and valve manifold units and the outboard fluid-driving system consisting of a fixed displacement axial piston fluid motor and propeller.

PATENTED mm 3.587.511

SHEET 1 0F 4 mvnrwon CURT BUDDRUS PATENTEOJuN28|9n 3,587,511

sum 2 0F 4 CU RT BUDDRUS HYDRAULIC MARINE PROPULSION SYSTEM BACKGROUND OF THE INVENTION The present invention relates to hydraulic boat propulsion, particularly a new application of hydrostatic power for propelling, controlling and braking a marine vessel.

SUMMARY OF THE INVENTION The hydraulic propulsion system of the present invention utilizes an inboard reversible variable displacement axial piston pump controlled by a single hand lever operated servosystem in conjunction with an outboard fixed displacement axial piston-type fluid motor driving the vessel propeller. A charge pump and servo valve system control fluid flow and pressure.

The propulsion system disclosed herein provides the operator with infinite variable forward and reverse speeds through the almost effortless operation of a single control lever. The operator can reverse the propeller from full speed ahead to full speed astem creating an extremely powerful braking force. Thus, a safety feature is built into the present propulsion system not available in conventional hydraulic clutch systems which are limited in capacity and subject to stripping of gears under shock. The rapid reversal of direction under full power achieved by the present invention enhances maneuverability in general.

With the motor disclosed in the present invention, the propeller is locked instantly when the control lever is placed in neutral, a great asset and safety feature, particularly when towing skiers.

The present propulsion system is simple and employs a minimum of moving parts. The system is thus uniquely constructed of unit package assemblies. The motor, for example, can be removed in a few minutes and replaced by a new or rebuilt unit. The fluid pressure generating assembly is composed of five units, i.e. the pump unit, the servo unit, the speed control unit, the charge pump unit and the valve manifold unit. The units are packaged into one housing and can be easily and quickly removed for maintenance and replacement.

The present propulsion system does not require opening the vessel below the water line. Thus, the problems encountered with presently known inboard operation and mechanical outdrive operation, such as leakage from stuffing boxes, openings sealed with rubber diaphram's, and water intakes and tubes, are eliminated.

In the present invention, the out-drive unit is fastened to the transom of the vessel in such manner that inthe event of accidentally striking an object hard enough, the out-drive unit will simply be torn away avoiding damage. With conventional inboard driven vessels, accidentally passing over an object frequently results in the strut and rudder being broken loose from the hull creating a serious leak. A similar accident to a vessel equipped with a conventional out-drive unit can result in the drive being broken off leaving a large hole at the water line swamping the boat.

With the present invention, the basic power plant and reversible variable displacement axial piston pump can be positioned at any desired point within the vessel. Thus, perfect balance is obtainable permitting the design of faster hulls.

Although power is transmitted in the present invention through a fluid, oil, it is virtually incompressible. Thus, the drive of the presentinvention is solid and firm while response more positive than with conventional mechanical marine drives since the slack or play present in gears, clutch, universal joints, splines and couplings is eliminated.

The fixed displacement axial piston fluid motor and propeller unit is light in weight and small in size relative to its high torque delivery and can be attached to the hull at a position preselected to minimize drag.

The fluid motor has low housing pressures permitting the use of aluminum for building the out-drive unit. In contrast, the housing for a gear or vane type motor must withstand extremely high operating pressures exceeding the point at which aluminum can be used practically as a housing. In addition, gear or vane type motors depend upon the wiping contactof the rotating parts with the interior surfscedf the housing. Aluminum will not withstand this type of severe service.

The fixed displacement motor of the present invention provides additional advantages over prese'nt commercial embodiments, such as the crescent-type gear motor, gear on gear motor, gear within gear motor and vane-type motor. In the motor disclosed in the present invention the pressure range is higher, the running torque is higher, the running volumetric efficiency is higher, the running life at full load is better and reversibility excellent.

The present propulsion system is completely self-contained and thus self-lubricating.

Finally, the motor is protected from shock and overloading by the valve manifold system.

BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is a side view partly in section and partly schematic illustrating generally the present hydraulic marine propulsion system including the inboard power plant, the inboard fluid pressure-generating system comprising the pump, servo assembly, speed control, charge pump and valve manifold units and the out-drive system comprising the fluid motor and propeller unit and the assembly for mounting same to the vessel;

FIG. 2 is a sectional view of the propulsion system illustrating the relationship of structure and fluid flow in neutral position;

FIG. 3 is a sectional view of the propulsion system illustrating the relationship of structure and fluid flow in forward position; and

FIG. 4 is a sectional view of the propulsion system illustrating the relationship of structure and fluid flow in reverse position.

DESCRIPTION OF THE PREFERRED EMBODIMENT A vessel generally designated by the reference numeral 10 and terminating in transom 12 is illustrated in FIG. 1. v

Within vessel 10 are located a conventional power plant 20 including a flywheel 22 and the fluid pressure-generating system 30 consisting of the reversible variable displacement axial piston pump unit 32, the servo assembly unit 34, the speed control unit 36, the charge pump unit 38 and the pressure control valve manifold unit 40.

The out-drive unit is generally designated by the reference numeral 70 and includes the fixed displacement axial pistontype fluid motor 72 provided, as seen in FIG. 2 with swashplate 74, pistons 75, output shaft 76 and the propeller 78 attached thereto.

A hanger assembly 80, as seen in FIG. 1, supports the outdrive unit 70 and includes a plate 82 mounted to the transom l2 and having a hydraulic rotary actuator 84 secured thereto. Fixedly mounted upon the shaft 86 of the actuator 84 is a hanger clevis 88 which supports a second hydraulic rotary actuator 90 having its shaft 92 keyed to the support 94 of the out-driveunit 70. The hanger assembly supports the outdrive unit from the transom 12 while actuators 84 and provide tilting and steering, respectively, as disclosed in detail in application Ser. No. 826,913, filed May 27, 1969, and entitled STEERING AND TILTING SYSTEMS FOR MARINE VES- SELS.

As will immediately be apparent, the power plant 20 and the fluid pressure-generating system 30 can be located at any desired point within the vessel 10 permitting the design of faster hulls. Also, the separate fluid motor 72 and propeller 78 are light in weight and small in size and, thus, capable of being attached to transom 12 at a point selected to minimize drag.

There is no necessity for holes or openings below the water line. In this manner, conventional mechanical linkage assemblies are eliminated and damage to the transom resulting from accidents caused by striking objects in the water effectively eliminated.

The entire propulsion system is self-contained and thus selflubricating. A minimum of moving parts are employed and the entire propulsion system constructed of unit package assemblies, i.e. the power plant 20, the pump 32, servo assembly 34, speed control 36, charge pump 38 and valve manifold 40 units of the fluid pressure-generating system 30 and the fluid motor 72.

Operation of the circuits of the present propulsion system is explained as follows with reference to FIGS. 2-4.

THE CHARGE PUMP CIRCUIT Oil flows from a reservoir 41 through a ten micron filter designated by reference numeral 42 and a vacuum gauge 43 to the inlet 44 of the charge pump assembly 38 which is mounted upon the main pump 32 which is driven by the input shaft 45. The purpose of the charge pump 38 is to provide a flow of oil through the system for cooling purposes, to supply oil under pressure to maintain a positive pressure on the low pressure side of the main pump circuit, to provide sufficient oil under pressure for control purposes and for internal leakage makeup.

THE MAIN PUMP AND MOTOR CIRCUIT Oil from the charge pump 38 is directed to the low pressure side of the main circuit by means of one of the check valves 46, 46' while the other of the check valves 46, 46' is held closed by the oil under high pressure on the other side of the main circuit. The main circuit is designated by the reference numeral 47 in FIGS. 2-4.

Oil flows in the main circuit 47 in a continuous closed loop. The quantity of oil flow is determined by the speed and displacement of the pump 32. A swashplate 48 is mounted within the pump 32 and connected to pistons 62 such that the direction of flow is determined by the angle of the swashplate 48 from neutral. Note FIGS. 2-4.

A valve manifold assembly 40 is connected across the main circuit 47 and includes the necessary elements essential to provide for proper operation of the system, including pilotoperated high pressure release valves 49 and 49' which prevent sustained abnormal pressure surges in either of the two main hydraulic lines by dumping the oil from the high pressure line to the low pressure line during rapid acceleration or sudden reversal at high speed for braking. See FIGS. 3-4 for identification of high and low pressure lines during the forward and reverse cycles. A shuttle valve 50 and a charge pressure release valve 51 are also provided within the valve manifold unit 40. Shuttle valve 40 functions to establish a circuit between the main line that is at low pressure and charge pressure release valve 51 to provide a method of controlling the charge pressure level while so removing excess cooling oil added to the circuit by charge pump 38. The shuttle valve 50 is spring centered toa closed position so that during the transition of, the reversing of pressure in the main lines none of the high pressure oil is lost from the circuit.

THE COOLING CIRCUIT Excess cooling oil from the manifold charge pressure release valve 51 enters the motor 72 and then flows through the motor casing drain line 52 to the pump 32. In this manner, cooling oil from the charge pump 38 is circulated through each of the hydraulic elements in series and then exits from the pump casing line 53, passes through the heat exchanger assembly 54 provided with cooler bypass valve 55 and is returned to the reservoir 41. The bypass valve 55 prevents high case back pressure at the heat exchanger due to the cold oil or a restricted cooler. During periods of operation when the main pump 32 is in neutral, the shuttle valve 50 is closed and excess oil fro'rnthe charge pump 38 is directed to the cooling circuit by the neutral charge relief valve 63. When operating at this condition, cooling flow is not admitted to the motor 72 since it is at rest.

THE CONTROLS Control of speed and direction is accomplished by the movement of the single control lever 56 from its neutral position. Two opposed single acting servo cylinders 58, 58' contain pistons 64, 64' connected to swashplate 48 by rods 65, 65'. The swashplate 48 is loaded by springs 57, 57' to its neutral positionl The servo pistons 64, 64' move the swashplate 48 and thus vary the displacement of the pump 32. Pressurizing one of cylinders 58, 58' through lines 66, 66' while exhausting the other moves the swashplate 48 from its neutral position. To obtain the reverse direction from neutral, the system is merely reversed. See FIGS. 3-4. Oil is directed to the desired servo cylinder 58, 58' by control of valve 59 which is activated by a signal from the operator through the control lever 56 and linkage system 60 or from the swashplate 48 and its feedback linkage system 61. If the circuit pressures tend to overcome the swashplate servo piston preset position, the feed back linkage system 61 connecting the swashplate 48 to the control valve 59 will activate same and supply adequate pressure to the appropriate servo piston 64, 64 while maintaining swashplate 48 in its position determined by the operator. The control valve 59 is spring centered and contains sufficient underlap to open both servo cylinders 58, 58' (FIGS. 34) and to drain when the control lever 56 is positioned in neutral (FIG. 2). This permits the servo cylinder centering springs 57, 57' to move the swashplate 48 to the zero stroke position insuring a positive neutral position.

As will now be apparent, control of the variable displacement axial piston pump 32 is a major factor in the present invention. When the operator moves the control lever 56, the swashplatc 48 is tilted from neutral. The position of the control lever 56 determines the angle of the swashplate 48 and, therefore, the volume of oil displaced by pump 32. The con trol lever 56 is stcpless and therefore the direction and speed of the vessel is infinitely variable from zero to maximum.

When the swashplate 48 is tilted, as seen in FIG. 3, a positive stroke to the pistons 64, 64 results. This, in turn, at any given engine speed produces flow from the pump 32 which is transferred through the high pressure lines to the motor 72. The ration of the volume of flow from the pump 32 to the displacement of motor 72 determines the speed of the output shaft 76 of the motor 70. When the control lever 56 is moved to the opposite side of neutral, as seen in FIG. 4, the flow from pump 32 is reversed and the output shaft 76 of the motor 72 turns in opposite direction. The speed of the output shaft 76 of the motor 72 is controlled by adjusting the displacement or flow of the system. Load or working pressure is determined by the thrust required by the propeller 78 which establishes the demand on the system.

As will be apparent, the present system is designed for sudden and rapid reversal of direction under full power without shock to the system. Thus, the present system contributes to marine safety and vessel maneuverability.

The operator is provided with infinite variable forward and reverse speeds through the almost effortless operation of a single control lever 56 which is pushed forward for forward speed, stopped in the upright position for neutral which also locks the propeller 78 and pulled backward for reverse speed, the amount of travel of the lever 56 governing the speed.

Although power is transmitted through a fluid oil the resulting drive is solid and response more positive than can be achieved by mechanical marine drive systems.

Since the fluid motor 72 has very low housing pressures, 40 p.s.i. or less, the entire outdrive unit 70 can be constructed of aluminum.

Finally, it is readily apparent that one pump can be used with two motors, two pumps can be used with two motors and substantial variation in the size of pumps ,and motors possible to obtain the desired speed and power output ratios. System pressure should be at 3000 p.s.i. for average operating conditions and 5000 p.s.i. obtainable for intermittent overloads due to emergency demand. By holding pressures in this range overall efficiencies up to 95 percent are possible, in contrast to efficiencies of 45 percent for present day mechanical stern drive units and 70 percent for inboard drive units.

Manifestly, variation in structure and circuitry may be envisioned without departing from the spirit and scope of invention as defined in the subjoined claims.

l claim:

1. A propulsion system for a vessel, comprising:

a power plant;

main in-line axial piston fluid pump means operatively connected to said power plant, and including means for regulating the direction and displacement of fluid therethrough;

servo means operatively connected to said pump for actuating said means for regulating displacement of fluid through said pump; 1 control valve means operatively connected to said servo means for actuating and controlling said servo means; charge pump means;

pressure control valve manifold means;

a fixed displacement axial piston fluid motor and a propeller operatively connected thereto;

first fluid circuit means connecting said main pump, motor,

and pressure control valve manifold means; and

second fluid circuit means connecting said charge pump means and said main pump and said charge pump means, servo means and control valve means.

2. A propulsion system as in claim 1 said pump including a plurality of pistons, said means regulating the displacement of fluid through said pump including a swashplate mounted within said pump operatively connected to said pistons and normally biased in neutral position, said servo means including a plurality of servo cylinders operatively connected to said swashplate such that as said control valve means is operated certain of said servo cylinders are pressurized while certain of said servo cylinders are exhausted, moving said swashplate from neutral varying the displacement and timing of the stroke of said pistons.

3. A propulsion system as in claim 2, said main pump means, charge pump means, pressure control valve manifold means and motor comprising separate structural entities.

4. A propulsion system for a vessel, comprising:

a power plant;

a main fluid pump operatively connected to said power plant, including means regulating the direction and displacement of fluid therethrough; servo means operatively connected to said means for regulating displacement of fluid through said fluid pump; valve means operatively connected to said servo means for actuating and operating same;

charge pump means;

a fluid motor and a propeller operatively connected thereto;

first fluid circuit means operatively connecting said pump and motor; and

second fluid circuit means operatively connecting said charge pump means and said main pump and said charge pump means, valve means and servo means.

5. A propulsion system as in claim 4, said means for regulating displacement of fluid through said fluid pump including a swashplate, means normally biasing said swashplate in neutral position, means mounting said swashplate within said pump, pistons, means operatively connecting said swashplate to said pistons, said servo means including first and second opposed servo cylinder assemblies, means connecting said assemblies to said swashplate, said valve means including means pressurizing said first servo cylinder assembly, while exhausting said second assembly to move said swashplate from its neutral position and pressurizing said second servo cylinder assembly while exhausting said first assembly to move said swashplate from its neutral position in the opposite direction.

6. A propulsion system as in claim 5, said second fluid circuit means operatively connecting said charge pump means and said mam pump including separate conduit means to each of said pistons of said pump and a check valve positioned in each said conduit means.

7. A propulsion system as in claim 6, said fluid motor being a fixed displacement axial type.

8. A propulsion system as in claim 6, said valve means comprising a casing, first and second conduit means formed as a part of said second fluid circuit means connecting said valve casing and said servo cylinder assemblies, a movable valve member, and means mounting said movable member within said casing to selectively deliver fluid through said first and second conduit means to selectively pressurize said first and second servo cylinders, as desired.

9. A propulsion system as in claim 8, said second fluid circuit means including means connecting said charge pump means and the inside of said main pump and motor for cooling same.

10. A propulsion system as in claim 5, said fluid pump being an in-line axial type. 

